Generally speaking, this invention relates to a device for imparting centrifugal force to samples in order to separate a heavier and a lighter fraction in each of the samples. More particularly, this invention relates to a device which may utilize both an agitating vertical movement to impart a stirring action to a sample, followed by a centrifugal force applied to the sample. The device of the invention utilizes a single drive for this purpose.
This invention is related to the subject matter in co-pending U.S. patent application Ser. No. 477,733, filed Feb. 9, 1990, and is hereby incorporated by reference in its entirety.
It is conventional to obtain fluid samples, and particularly body fluid samples, and place them in a centrifuge to separate the heavier and lighter fractions in the sample for subsequent examination and testing for indications of the presence of disease, etc. in the samples taken from an individual. However, in certain circumstances, it is important to impart a stirring action to the sample under consideration prior to the application of centrifugal force. This may be so if a material is added to the sample for reaction with the sample prior to centrifugation and separation of the resulting heavier and lighter fractions. It is to this concept that the present invention is directed.
In certain environments such as the operating room, it has become important to provide facilities for taking body samples of various kinds from an individual, which are worked upon in some manner, and returned to the body in some manner. All of this, as will be understood, must be done fairly rapidly and in a sterile environment.
For example, it has been recognized that human microvascular endothelial cells, i.e., the cells which are derived from capillaries, arterioles, and venules, will function suitably in place of large vessel cells even though there are morphological and functional differences between large vessel endothelial cells and microvascular endothelial cells in their native tissues. Microvascular endothelial cells are present in an abundant supply in body tissue, most notably in fat tissue, and may be used to established a degree of pre-implantation confluence, i.e., at least fifty percent, which should dramatically improve the prognosis of most implants. Thus, fat tissue may be taken from a patient in the environment of an operating room, and that fat tissue acted upon in order to obtain microvascular endothelial cells which may be then implanted on the surface of synthetic grafts which are implanted to substitute for the natural blood carrying vessels in the body.
Although microvessel endothelial cells have been shown to be capable of endothelializing a blood-contacting surface, methods of procuring and depositing these cells in an operating room setting present special considerations.
The microvascular rich tissue is obtained in perinephric fat, subcutaneous fat, or fat associated with the thoracic or peritoneal cavity. This tissue is then subjected to digestion using a proteolytic enzyme, such as collagenase, comprising caseanase and trypsin, which is incubated with the tissue until the tissue mass disperses to reduce a tissue digest. It is during this period, that the invention may be utilized in order to agitate this combination to obtain a certain result. Thereafter, the microvascular endothelial cells are then separated from the digest that has already taken place using centrifugation to produce an endothelial cell rich pellet. The pellet may then be dissolved in an appropriate suspension and the resulting cells applied to the surface of a graft. As a result, an improved graft implant is provided having endothelialized surfaces which are either confluent or which reach confluence guite rapidly (within one population doubling) following implantation.
A special feature of the invention here, as stated above, is that the device of the invention allows digestion with agitation followed by centrifugation, with these movements being selected, as desired in the controls of the single device of the invention. It will be understood, however, that the environment discussed above is not the only environment in which the device of the invention may be used. It may be used, as will be apparent to practitioners-in-the-art, in any application where agitation movement may be required selectively with centrifugation, as required in any process.
With the foregoing and additional objects in view, this invention will now be described in more detail and other objects and advantages hereof will be apparent from the following description, the accompanying drawings, and the appended claims.